This report was translated by AI; nobody has reviewed the translation yet. Original language: Czech.

[TLP:CLEAR] Zyxel fixes 2 vulnerabilities

Zyxel fixes 2 vulnerabilities in specific firmware versions of its products: - 4G LTE/5G NR CPE - DSL/Ethernet CPE - Fiber ONTs - Security Routers - Wireless Extenders A clear table of all fixed versions and the corresponding devices can be found at [1].

Zyxel DSL/Ethernet CPE, Fiber ONTs, Wireless Extenders - OS command execution (CVE-2025-8693)
CVSS 8.8 (High)

An authenticated remote attacker can execute commands on the operating system of the affected device through certain firmware versions of DSL/Ethernet CPE, Fiber ONTs and Wireless Extenders [1][2]. WAN access is disabled on these devices by default, which reduces the risk of exploitation; in addition, a strong user password would have to be compromised [1].

CVSS: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

More information:

  • CVE-2025-8693 at cve.org, NVD
  • CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') at cwe.mitre.org

The vulnerability was publicly disclosed 18. 11. 2025.

Zyxel 4G LTE/5G NR CPE, DSL/Ethernet CPE, Fiber ONTs, Security Routers, Wireless Extenders - DoS (CVE-2025-6599)
CVSS 5.3 (Medium)

An unauthenticated remote attacker can perform a DoS attack (Slowloris) on the web administration interfaces of certain firmware versions of 4G LTE/5G NR CPE, DSL/Ethernet CPE, Fiber ONTs, Security Routers and Wireless Extenders [1][3].

CVSS: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

More information:

The vulnerability was publicly disclosed 18. 11. 2025.

By CESNET, z.s.p.o. Michaela Ručková on 24. 11. 2025.

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